Bilateral paramedian thalamo-midbrain infarction showing electroencephalographic alpha activity.

A 57-year-old man became unresponsive and mute with bilateral ophthalmoplegia and quadriplegia. Magnetic resonance imaging (MRI) showed bilateral infarctions at the ventral midbrain and the dorsomedial nucleus of the thalamus. Serial studies with MR and vertebral angiography disclosed hypoperfusion and spontaneous reperfusion of the bilateral posterior cerebral arteries at their origin from the basilar artery. Electroencephalographically, a posteriorly distributed alpha rhythm was clearly recorded and it was reactive in response to external stimuli. The findings seen in the present patient suggest that the ventral midbrain and medial dorsal thalamus are not necessary to produce posterior electroencephalographic alpha activity.